Train control system



Oct. 25,1949. H. P. FOLKER 2,486,271

TRAIN CONTROL SYSTEM Filed March 10, 1947 I Sheets-Sheet l lNl/EN TOR Byerber/ Fo/A er ATTORNEY Oct. 25, 1949. H. P. FOLKER TRAIN CONTROLSYSTEM 3 Sheefts-Sheet 2 Filed March 10, 1947 mi k e 5 WP A 5 l wk 1 5gay 444 /M% AW aa w Oct. 25, 1949. H. P. FOLKER v TRAIN CONTROL SYSTEM-3 Sheets-Sheet 3 Filed March 10, 1947 I N VE N TOR Herbs/f l? Fb/ker- YPatented Oct. 25, 1949 TRAIN CONTROL SYSTEM Herbert P. Folker, Oakland,Calif., assignor to National Safety Appliance 00., Ltd., San Francisco,Calif., a corporation of California Application March 10, 1947, SerialNo. 733,476

Claims. 1.

This invention relates generally to train control systems of the typeadapted to efiect automatic brake applications and to enable a manualforestalling operation to prevent brake application under certainconditions.

In the past train control systems have been known which incorporatemeans on the locomotive adapted under certain conditions to receive atrack impulse which serves to vent the main brake pipe of the pneumaticbrakin system of the train to thereby efiect an automatic application ofthe brakes. Forestalling devices such as are used with such systemsincorporate a time delay mechanism having an automatic cycle which isput in operation when the engineer actuates a forestalling lever. In theevent a track impulse is received by the system during the time delayafiorded by the forestalling mechanism, a brake applicationdoes notoccur. Should the engineer fail to make timely operation of theforestalling lever, an automatic brake application occurs in response toa track impulse, and the train is then stopped, thus requiring theengineer to thereafter carry out a release or restoring operation. thetype described in Folker et a1. 1,439,081 and 1,690,816 a magnetic trackimpulse is utilized which directly operates one of a pair of valvesincorporated in a duplex control valve, whereby a line leading to anautomatic stop valve is vented to secure a brake application. Theforestalling unit as previously utilized with a system of the Folkertype (see Patent 1,592,930) serves to automatically shut off the lineleading from the automatic stop valve to the duplex control valve, andto vent the line leading to the duplex control valve to thereby preventoperation of the same in response to a track impulse for a given periodof time.

Forestalling units of the type disclosed in Folker 1,592,930, or asmodified to include a forestalling unit of the hydraulic type, have notbeen well adapted to operation of the forestalling unit from a positionremote from the time delay means employed. This is a disadvantage inmaking installations on modern passenger trains, such as trains of thestreamlined Diesel type, because it is frequently desirable in suchinstallations to provide a small manually operated device at a positionat a considerable distance from the time delay means of the forestallingunit, for initiating the iorestalling operation.

An additional disadvantage of the prior Folker train control system, asdescribed above is that when the iorestalling unit is located a In traincontrol systems of l 2 considerable distance from the automatic stopvalve and from the duplex control valve, the length of the connectinpipes is such that pressure cannot be quickly built up in the pipeleading to the duplex train control valve, with the result that at theend of the forestalling period when the shut-01f valve previouslydescribed is automatically opened, pressure from the automatic stopvalve may be lowered to such a point that an automatic brake applicationoccurs.

It is an object of the present invention to improve the Folker. type oftrain control system whereby the forestalling means is simplified andmade adaptable to a wide variety of installations,including'installations where the member which is manually actuated fora forestalling operation is located aconsiderable distance from theforestalling time delay means.

A further object of the invention is to improve upon systems of theabove character whereby the pipe leading from the forestalling unit tothe duplex train control valve may be extended to any length desired,without causing an undesired brake application at the end of aforestalling period.

Another objectoi the invention is to provide a novel and automatic meansfor quickly recharging the line leading from the forestalling unit tothe duplex train control valve with air under pressure from a secondarysource, at the end of a forestalling period.

Additional objects and features of the inven-. tion will appear from thefollowing description in which the preferred embodiments of theinvention have been set forth in detail in conjunction with theaccompanying drawing.

Referring to the drawing:

Figure 1 is a diagrammatic view, partly in section, illustrating a traincontrol system incorporating the present invention.

Figure 2 is a diagrammatic view, partly in section, illustrating theforestalling unit and associated parts incorporated in Figure 1.

Figure 3 is a diagrammatic View illustrating a modification of Figure 1to incorporate line charging means.

Figure 4 diagrammatically illustrates a control system similar to Figure3 but with direct manual rather than remote operated forestalling means.

Figure 5 is a diagrammatic view in section illustrating the constructionof the direct manual forestalling unit illustrated in Figure 4.

The train control system as illustrated in Figure 1 consists of a duplextrain control valve l0 of the type adapted to be operated by a magnetictrack impulse and as disclosed for example generally in Letters Patent1,439,081, 1,439,082, 1,592,930 and 1,690,816. As presently explained indetail the duplex control valve I is used in conjunction with therelease or restoring valve II, the automatic stop valve l2 (see1,529,058) and the forestalling unit l3. Located at a point remote fromthe forestalling unit l3 there is a manually operated forestalling valvel4. In addition to the parts just mentioned the system may include anair strainer l6, 3. double heading interlocking valve l1, and a doubleheading outout cock 3.

The release or restoring valve H, and valves l1 and H3, can besubstantially as shown and described in Folker 1,690,816.

The piping for the various parts mentioned above is as follows: Acontrol pipe 20 extends from the duplex control valve II] to therestoring valve H, and an extension 2| of the same extends from therestoring valve to the forestalling unit. Line 22 which connects to theautomatic stop valve I2 is the brake application pipe of a conventionalpneumatic train braking system. Pipe line 23 leads iromthe stop valve l2to the engineers brake valve, and is equipped with a double heading cockl8. Line 24 represents a connection to the main air supply reservoir ofthe braking system. Line 26 is an extension of line 24 beyond the filterI6 and connects with the time delay means of the forestalling unit aswill be presently explained. Pipe line 21 connects from the stop valve|2 to certain parts of the forestalling unit as indicated and in effectis an extension of the control line 2|. Another pipe 28 connects stopvalve |2 with the air supply pipe 26. Pipe 29 connects the restoring orrelease valve II with the interlocking device l1, and line 3| connectsthis device to the double heading cock l8.

For a normal position of the various parts, that is a position in whichthe system is in condition to be responsive to a track impulse to effectan automatic brake application, brake pipe 22 is maintained closedagainst venting to the atmosphere by the stop valve l2, while airpressure is maintained in control pipes 20 and 2|, and cock |8 is opento permit control of the braking system from the engineers cab. Pipe 28leads to the main air reservoir and is in restricted communication withthe control pipes 20 and 2|. Each of the two valves in the duplexcontrol valve H! are retained closed magnetically, and when the controlvalve passes over a track magnet, the field of which has not beenneutralized by a signal current, one of the two duplex control valves(normally held closed magnetically) is open to vent the control pipe,the particular valve operated dependent upon the direction of movementof the train. Venting of control pipe 20 to the atmosphere resultingfrom opening of one of the two control valves, reduces holding pressureupon the operating diaphragm of the stop valve l2, and as a result thevalve member of the stop valve moves to a position to cause venting ofthe brake pipe 22 to the atmosphere, and the non-release valveincorporated in the same closes communication between pipes 23 and 22.

The forestalling unit incorporated in Figure 1, together with the remoteforestalling valve I4, is illustrated in greater detail in Figure 2. Theforestalling means illustrated consists of time delay means of thehydraulic type, including a Ill reservoir 33 adapted to contain aquantity of suitable liquid such as oil. Restricted orifice 34establishes communication between the lower portion of reservoir 33 andthe lower portion of a vertically extending cylinder 36. A piston 31 isslidably fitted in cylinder 36 and is attached to the lower end of a rod38. The upper end of rod 38 is attached to a member 39 which can betermed a piston valve, and which is slidably fitted in a second cylinder4|. Piston 31 is provided with suitable sealing means such as the cupleather 42, and like means such as a cup leather 43 is provided forpiston 39. A compression spring 44 is shown positioned at the lower endof cylinder 36 and is adapted to be compressed when the piston 39completes its final downward movement. The lower portion of the cylinder4| is provided with ports 46 and 41 which are closed by the piston valve39 for the lowermost, position of the same as illustrated in Figure 2,but which are exposed for communication with the upper portion ofcylinder 36 when the piston valve moves up- Wardly.

As will be presently explained during a forestalling period piston 31together with piston valve 39 is caused to move upwardly at a regulatedrate by application of line pressure to the reservoir 33, and afterreaching the upper limit of their travel, these members move downwardlyto their initial position. The space above piston 31 is in continuouscommunication with the main reservoir supply pipe 26.

In conjunction with timing means I provide a shut-oil valv 5| togetherwith a valve actuator 52. The shut-off valve is double seated andconsists of a movable valve member 53 carried by the fluted stem 54. Thevalve member in its one limiting position closes upon a stationary seat56 and in its other limiting position on seat 51 surrounding the stem54. The orifice 56 connects with the pipe line 21 as illustrated, and aspace between seats 56 and 51 connected with the control line 2|. In thenormal position of the shutoff valve as illustrated in Figure 2, lines,2| and 21 are placed in free communication. However when stem 54 isactuated to close valve member 53 upon seat 56, line 2| is vented to theatmosphere past stem 54 and line 21 is closed.

The actuator 52 consists of a body forming a cylinder 58 and fitted withthe piston 59. The space on one side of piston 59 connects with thesignal whistle 6|, and with line 62 which connects with the port 41 ofthe timing means. Thus when air pressure is applied to pipe or duct 62piston 59 is urged in a direction to move stem 54 and thereby closevalve member 53 upon seat 56. While such pressure is applied to pipe 62the signal whistle 6| is operated.

In addition to the foregoing the forestalling unit includes thepneumatic actuator 63, and a combination vent and closure valve 64.Actuator 63 consists of a body 66 fitted with the cylinder 61. A piston68 is fitted in cylinder 61 and is attached to the rod 69. A tube II isalso attached to red 69 and extends to the exterior of the device. Aplunger 12 provided with a projecting stud 13 is slidably fitted withintube H and is yieldably urged toward projected position by thecompression spring 14. Another compression spring 16 urges the pistontogether with the tubular member toward retracted position. Duct 11communicating with one side of piston 68 is connected by pipe 18 to theport 46 of the timing means, and also by pipe 19 to the remote valve l4.

"Valve 64 consists of a valve member 8| adapted to-close upon thestationary seat 82 and carried by the stem 83. The valve stem isprovided with a duct 84 which communicates with the orifice 86 formed onthe outer end of the stem. The outer end of the stem loosely carries acup 81 provided with'vent openings 88, and with a seating disc 89. Oneside of the seat 82 is connected by pipe 9| with the line 21 leading tothe automatic stop valve. connected by line 92 to a duct 93 in thetiming means whereby this pipe is in communication with the space in theupper part of the liquid reservoir 33.

Y The timing means, the pneumatic actuator 63 and the valve 64 arecorrelated by latching means which can be constructed as follows: Alatch lever 94 as diagrammatically illustrated has a stationary' pivotalmounting 95 and has a portion of the same interposed in the path ofmovement of the piston valve 39. The free end of lever 94 carries whatcan be termed a latch bolt 96, the lower end of which for purposes ofschematic illustration is normally interposed between the aligned stud13 and the cap 81. The arrangement of parts in this connection can besimilar to that illustrated in Patent 1,592,930 (see Figures 5 and 6 ofsame) assuming that the plunger stem 74 corresponds to the plunger stud13 in the present instance. The latching means just described can besimilar to that disclosed and. claimed in said Patent N 0. 1,592,930,and functions as follows: When no pressure is being applied to thepiston 68 of the pneumatic actuator 63 the parts occupy substantiallythe operating positions illustrated in Figure 2. Valve member 8| isclosed upon its seat 82 and line 92 is vented to the atmosphere throughducts 84, 86, and 88. When pneumatic pressure is applied to piston 68 byway of duct 11, movement of this piston transmits motion to the stud I3and such motion is transmitted through the lower end of latch bolt 96,to close cap 81 upon orifice 86, and to move the valve member 8| to openposition with respect to seat 82. after when piston valve 39 strikeslatch lever 94 and swings the same upwardly a limited distance, latchbolt 96 is retracted from its normal position between stud 13 and cap81, whereby valve member 8| is permitted to close and cap 81 permittedto move to open the venting orifice 86. As willpresently be explained ingreater detail this initiates a downward movement of the piston valve 39and after piston 3! has completed its downward movement, pneumaticpressure upon piston 88 is relieved whereby this piston is permitted toreturn to its initial position under the urge of compression spring 16,thereby enabling the latch bolt 96 to again drop down into its formerposition illustrated in Figure 2.

The remote valve l4 may be located a considerable distance from themainparts of the forestalling unit. It consists of a body l8| providedwith a valve member |82 normally urged by spring I83 against stationaryseat I84. A fluted stem 58? is attached to the valve member and isadapted to be engaged by the lower end of an operating rod I87. Theoperating rod extends to the exterior of the valve body where it isprovided with an operating button I88. Within the body the operating rodis attached to a, piston I89 fitted in the cylinder One side of thepiston I89 is vented to the atmosphere through the space about rod I81,and the other side is normallyin communication with the outflow pas- Theother side of seat 82 is Theresage H2. The inlet passage I I3 of thevalve is connected to the main reservoir supply pipe l I4, while theoutflow passage 2 connects with the line 19, which connects with thepneumatic actuator 63 and with the timing means.

Operation of the system as described above with reference to Figures 1and 2, can be reviewed as follows: Assuming that the system is in normalcondition ready to receive a track im-- pulse, and that the doubleheading cock I8 is turned to open position to permit control from theengineers cab as desired, the two valves of the duplex control valve I8are in closed position and retained closed against the pressure of airin control pipe 28, by the magnetic field of supermanent magnet asdescribed in aforesaid Patent No. 1,548,593. The paths of theforestalling unit are substantially in the position as illustrated inFigure 2, and the double seated shut-01f valve 5-l is in the positionillustrated whereby pipes 2 I and 2| are in free communication. Byvirtue of pressure maintainedin pipe 21 the valve member of theautomatic stop valve I2 is maintained in such a position that the valvemeans of the same maintains pipe 22 in nonventing condition. At the sametime however pipes 28, 2| and 21 are in'restricted communication withthe mainjsource'of air supply through the stop valve.

Assuming that a track impulse is received by the duplex control valvewithout operation of the forestalling unit, line 28 is vented totheatmosphere by the opening of one of the valve members of the duplexcontrol valve, and it serves to vent line 21 from the stop valve l2,whereby the stop valve automatically operates to vent'the brake pipe 22to the atmosphere. This serves to efiect an automatic brake application.In order to restore the system to normal operation the engineer mustthen move the handle of the restoring valve H to restoring position,whereby pipe 28 is vented to the atmosphere and temporarily disconnectedfrom pipe 2|, and pipe 2| is connected to pipe 29 and thereby vented tothe atmosphere through the interlocking valve IT. This retains thebrakes applied and permits the pressure in pipe 28 to drop toatmospheric, whereby the valve member of the duplex control valvewhich'has been actuated to open position, is permitted to return toclosed position. Thereafter when the handle of the restoring valve II isreturned to normal position, pipe 28 is reconnected with pipe 2 I. vAssuming now that the engineer is alert and carries out a forestallingoperation to prevent a brake application by a track impulse, button 188of the remote forestalling valve I4 is depr'essed whereby valve I82 isunseated to permit application of air pressure from the main supplythrough pipe 19 to the pneumatic actuator 63. Operation of actuator 63serves to close the venting orifice 86 and unseat the valve member 8|,whereby pressure from line 2'! through line 9| is applied through pipeor duct 92 and duct 93 of thetiming means to the space above the liquidin reservoir 33. Liquid from reservoir 33 now commences to flow throughthe restricted orifice 34 to the space beneath the piston 31. Theinitial movement of thispiston is aided by the compression spring 44.Piston valve 39 moves upwardly with piston 31, and when port 46 isexposed this port together with line 18 is placed in free communicationwith the space above the piston 31. In connection with the upwardmovement of the piston 31 it will be noted that the full pressure of themain reservoir supply is applied at all times to thespaceabo've piston=33. However the supper :area lOf piston 3.1 minus (the :upper area ofpiston .39 is less than :bottom area to which :the liquid -pressureapplied. fillhereiore a 'difierential :force acts to urge the pistonzupwardly. Exposure .of port 46 droxthe space above the piston appliesthe :full lmain reservoir pressure to the pipe 18, to the pipe 19 andthe pneumatic actuator .63. The pressure thus supplied to the actuator.can'be termed the molding pressure, and thereafter the-operatormaymelease the button 108, without interfering with automatic continuationof the forestalling cycle. :Release of button 1-118 permits this buttonto raise {to the position illustrated in dotted lines :in Figme 2, dueto the :fact that piston I09 is urged upwardly by pressure applied .topassage I I2.

Simultaneously with exposure of port 46 port 45 :is likewise exposed .tothe .line pressure exist-- ing .the upper portion of cylinder 36.Therezfore reservoir pressure is applied through 6.2 to thepneumaticoperator-52 whereby the piston .59 of this operator operatesthe shut-.ofi .valve .5l to close the valve member 53 upon seat 56..Thus shortly after the commencement of the iorestalling period thecontrol line 2| is :shut iofi item communication with the remainder ofthe control line .2], and .likewise that .portion .of the control lineleading to the duplex control valve by way .of pipe v2| is vented to theatmosphere. Thus a track impulse will not .operate either one of .thetwo control valves.

The piston 31.moves upwardly at a predetermined speed and when .itreaches substantially the 24 1 81 limit of its travel, piston valve 3.9

.strikes the latch lever 94 with the result that the liquid in reservoir33 to atmospheric pressure results in downward movement of the piston'31 under the urge of air pressure from the main reservoir supply.During the last portion of the downward travel of piston '31 ports 16and '41 are again exposed to the atmosphere about the upper ,part ofpiston valve '39, whereby an is no longer supplied to the pneumaticactuator '52. Thus the shut-off valve 51 is permitted to open and.reestablish .communication'between pipes '21 and 2 1.. discharging.from port 46 to the atmosphere reduces the pressure in pipes 18 and I9to atmospheric whereby button .lll8 is permitted to drop .down -.to itsnormal position by gravity. This serves to indicate to the operator thatthe forestalling-period has ended. The forestallingperiod and itstermination can also .be indicated by .a small signal whistle connected:to line 19..

.A particular -feature of the system .as described above is thesimplicity of the novel :means .em-' alloyed ior maintainingholdingpressure upon the pneumatic :actuator 63. As previously described this:is accomplished by the line 18 which :makes a ciinect connection:fromlthe actuator to the port 4'6. :Piston .valve :39 serves toautomatically contrdl the application of the main reservoir supplythrough the port 46 and the pneumatic :actuator whercbythe-holdingpressure isautomatically applied shortly after the .-f,or.estallingperiod (commemes and :is automatically :removed at the end ofthemestallmg operation. simple means eliminates the mecessity (of usingmore compli- :cated devices :for this purpo e. :as for :example orsupplemental diaphragm or pistomoperated valve. A ifiurther teat-are ofthe apparatus is the :use of .a booster :spring M below :the piston .31.This sprin speeds :up the initial movement of the piston 6.1., thusreducing the period of time are uired for the operator toihold thebutton zl 08 depressed.

in certain installations-of the system .described :above :it isdesirable to locate the forestalling unit :at a considerable distancefrom the duplex control valve. This introduces-{the problem of uicklyrecharging the extended pipe line leading from the duplex control valve,at the-.ondoi "a iorestalling operation. Where the control line .is of(considerable -length it .is impossible to charge the :same with :air.at the end of the ionsstalling operation by .air supplied from theauto- ;matic .stop valve, without causing undesired operationlof thelatter with false .momentary application of the train brakes. In thesystem of Figure ,3 this difficulty is overcome by the .uselof a linecharger -l 1.6. This line 'charger has one duct LI 1 connected withtheline 21 leading to .the .stop valve, another duct .8 which-isconnected to the control line .24 andaduct .l 1.9 which connects withthe line 26 leading from the .main reservoir supply, or some equivalentsupplemental source {of air. .In general this .line .charger serves tosupply charging air from the main reservoir sup- .ply orequivalent.supplementalsource to the control .line at the .end .of theIorestall'ing operation, .to quickly build .up the pressure in the same,after which the connection .to the supplemental source is automaticallydiscontinued Ior .normal operation of the system.

The particular line charger illustrated consists .ofaloody .i,2l withinwfhichare the two .valvernomhers A22. Each of these valve members is-.carried .by .a guided and .fiuted stem 1.23,, and is adapted :to closeunder the urge of spring .125 upon azs'ta- .tiona-ry .seat .124. .Asecond stationary .seat 1211a .can be provided about each .stem. Thelower portions of the stems 423 have central passages 12.6 which openthrough the lower ends of the stems into the space .1121. This space 'isvented to the atmosphere .as illustrated. Below the .stems .123 there is.a yoke .bar .123 which is provided with valve seat inserts I29. Theyoke bar J28 is interposed between two opposed pistons [31 and 132. Aretention stud 13.3 is carried by the :lower side of the yoke 428 and isfitted within :a central opening provided in piston .132. Space 434above the piston .13.! .isin restricted communication through orificell36 with the duct 1.118. and is in unrestricted communication withaclosed air chamber 1-13]. This chamber may .be a cavity iormed withinthe bodyof the device, or it may be .a separate chamber connected .tothe device by suitableextcnsionpipes. Space I33 below the.smal1er.piston.l.32 is conneoted by duct 139 with .a space -l4=l .aboue.theleft hand .valve member 112. and which spacelikewise communicateswith duct H1. Space M2 .above :the right hand valve member L22 is indirect communication with duct .1 fl 9. Intermediate space I43 surroundsthe inter- ,mediate portions of the-stems 1 23 and communicates with theupper portions of -ducts or passages 12.6. Thus when .both of the valvemembers .122 are closed as illustrated in Figure 3,.space 1 43.315vented to the atmosphere through the .ducts 1.25 and caw'ty L21.

Operation of the line charger described above .is as lfQllOWSI For anormal condition of the system with line pressure inoontrol lines 24 and9 21, valves I 22 are closed as illustrated. At the beginning of aforestalling operation double seated shut-01f valve is operated inamanner previously described to shut off communication between pipes 2|and 21, and to vent pipe 2I to the atmosphere. This serves to vent airthrough the orifice I36 from both spaces I34 and the cavity or chamberI31. This in turn results in such a reduction of pressure in space I34as to cause the lower (and smaller) piston I32 to force the yoke bar I28together with piston I3I upwardly to cause the seat inserts I29 toengage and lift the valve stems I23. This operation serves to move thevalve members I22 to full open position and at the same time ducts I26are closed to interrupt communication between spaces I21 and I43. Sealsare also established about the stems I23 because of engagement ofinserts I29 with seats I24a. When in open position spaces MI and I42 arein communication with space I43 through th flutes of the valve stemsI23. Thus pressure from the main reservoir supply line 26 is suppliedthrough space I42 and space I43 to the space I4I above the left handvalve member I22 where it assumes the same value as the pressure in pipe21. From space I4I pressure is transmitted through duct I39 to the spaceI38 below the smaller piston I32. Application of pressure to space MI ineffect forms a direct connection between the main reservoir supply line26 and the line 21 leading from the automatic stop valve.

At the end of the forestalling operation the double seated shut-offvalve 5| is moved to open position in the manner previously described,to re-establish communication between lines 2I and 21. Simultaneouslyair pressure from line 21 is supplied through the shut-off valve ill tolines 2I to 20 to quickly build up pressure in the latter to normalvalue. This charging operation does not substantially reduce thepressure in line 21 because during that interval this line is alsodirectly connected with the main reservoir supply line 26 or equivalentsupplemental source, through spaces I4I, the flutes of the left handvalve stem, space I43, the flutes of the right hand valve stem, andspace I42.

When the pressure in line 2| has been built up to substantially normalvalue, pressure in the chamber or cavity I31 has likewise increased tosuch a value that piston I3I is now urged downwardly with suificientforce to overcome the upper force of the piston I32. Therefore the yokebar I28 is moved downwardly to cause all of the parts to return tonormal position as illustrated in Figure 3.

Restriction I36 serves the useful purpose of retarding building up ofpressure in the cavity I31 toward the end of the charging interval.Cavity I31 provides an increased capacity for space I34 and thustogether with restriction I36 provides a proper interval" before cutout, that is before the pressure in space I34 builds up to a sufiicientvalue to move pistons I3I and I 32 in a direction to cause valve membersI 22 to close and interrupt further supply of air from the mainreservoir' supply or other supplemental source of air.

It will be apparent from the foregoing that the line charger asdescribed serves to automatically recharge the control lines connectedfrom the forestalling unit to the duplex control valve, withoutoccasioning a drop in pressure in the pipe line leading from theautomatic train stop valve.

Thus the lines connected from the forestalling unit to .the duplexcontrol valve may be any length desired without in any way interferingwith proper operation of the system. It will be appreciated that forconnecting lines of different lengths leading from the duplex controlvalve to the forestalling unit, the cavity or chamber I31 should beadusted accordingly as to volumetric capacity and likewise restrictionI36 can be adjusted. A larger cavity and/or a smaller restriction servesto increase the time period of the charging operation to adapt thesystem to longer connecting lines.

In the event a track impulse is received by the duplex control valve tocause actuation of the same, while the line charger is supplying air tothe line 21, the venting of air from line 2I will be insuflicient toprevent building up of pressure in the same, because of the relativelyhigh available rate of air supply from the charger.. There fore afterthe normal charging period valve members I22 of the line charger close,and thereafter continued venting by the duplex control valve causes abrake application.

The system illustrated in Figure 4 likewise uses a line charger I-I6 butthe forestalling unit in this instance is directly operated manually,rather than from a remote point. Thus the valve I4 in this instance isomitted, and in place of the pneumatic actuator 63 there is a hand leverI46 mounted upon the rotatable shaft I41. As diagrammaticallyillustrated the shaft carries a spring pressed lug I48 adapted to engageand transmit force to the lower end of the latch bolt I49. Thus when thehand lever is turned clockwise 270 as viewed in Figure 5, the cap 81ofthe valve 64 is operated whereby the valve member BI is unseated. Thisoperation is the same as when the pneumatic actuator 63 of Figure 2 isoperated by air pressure, and it effect-s commencement of a forestallingcycle. Latch bolt I49 is pivotally attached to the latch bolt I5I,corresponding to the latch arm 94 of Figure 2. When the piston 31reaches the upper end of its travel latch lever I5I is operated toretract the bolt I49, with a result that valve 64 is permitted to returnto its normal initial position, and the forestalling lever I46 permittedto return to its initial position as illustrated. In actual practice theparts just described can be similar to corresponding parts disclosed inPatent 1,592,930.

The direct manual forestalling means of Figure 5 cooperates with theline charger II6'in the same manner as the remote operated forestallingmeans of Figure 3. Here again the line charger serves to supply air tothe control line 2| at the end of the forestalling period to avoid animproper application of the brakes.

I claim:

1. In a pneumatic train braking system of the type including a controlvalve adapted to'vent a control pipe of the system in response to atrack impulse to thereby efiect automatic application of the trainbrakes, a valve adapted to be manually opened and having its inlet sideconnected to the main air supply reservoir of the system, and aforestalling unit set in cyclic operation by opening of said valve andserving to efiect shut off of said control pipe for a predetermined timetion towardthe said other end of the cylinder,

a= shut-offval've interposedin said: control pipe; another pneumaticactuator serving to operate saidshut-off' valve; another valve meansserving" to apply pneumatic pressure to said last named:

actuator duringthe travelaof said piston fromits' normal position, and:means: actuatedhy the" piston at the end of its: travel fromv saidinitial.

normal position for rendering the first. named: actuator inefi'ective=to" maintain its associated valve means closed.

2; A. system. as; inv claim. 1 in which the valve means: servingv toconnect. the chamberof the first named pneumatic actuator with, saidcylinder' consists oi: a second pi'stom attached to thefirst: piston; asecond: cylinder in which the sec-- ond piston operates;. and. a portexposed by the: second piston after initial movement of the same: and.connected to said first named actuator.

3:- In a: pneumatic'trainbraking system includ' ing a; control: valveadapted to. be'opened in response to a track impulse. tovent'a' controlline and an automatic: stop valve connected to the COIlflI'Oll linewherebywhen the; control line is vented said automatic-stopvalveventsthemain brake pipe" to thereby effect a brakeapplication, aiorestalling' unit. including; timedelay: means and ashut-offi valveoperated during? the time delay'period tointerrupt the'controlline' andto vent that? portion of said lineleading from the cone trol valve totheshut-off valve.- andoperated atthe' end of the? forestal'lin gi periodto reconnect saidporitiomot the control. line tothe automatic:

stopvalve, and automaticpneumatic line charg ing-means connected tot-hecontrol line and. serving to-supply air under pressure to thesame-onlyfor a, short interval: at the. endLof. theiforestalling period;

4.. Ina. pneumatic train braking systemincludling. a. control valve.adapted to be. opened in. re.- sponse to a track impulse to vent acontrol line and. an automatic. stop valve connected to the control linewhereby. when. the control line is vented said automatic stop valvevents the. main rorake pipe of the. train braking, system, atorestalling unit associated with the controlline;. said unit includingtime delay meanshaving an automatic cycle of operation adapted toteinitiated.

by an operator, and a shut-ofi'valve insaid control'lineandadaptediatthe beginning of the fore.-

stalling cycle to close that portionof the control.

rupt such, supply ofi. supplementalair: at; the: eachoffsaidlchargingiinterval.

5;. In". a. pneumatic train braking: system as; in: claim: 4' which saidline chargingmeans. has pneumatic: connections with. both thatvportioniof-T the control .lineleading from the automatic: stop valve and thatportion: leading from the control. valve,-. and incorporates valve meansfor automaticallv supplying that portion or the control line:leadingfrom the stop'valve: with air under." pressurefrom a:supplementali source ofi ain sup ply;, to recharge that portion ofthe.-control. line. leading fromthe-control valve, at the endoi. theforestalling'. cyola.

6; In: a. pneumatic-train braking; system as in. claim 4; in which. saidline-charger. comprisessa' body having a pneumatic connection. with themainreservoir supply of. they trainv braking sys.-- tem, a connection.to that. portion. of. the: control:

; linetleading from. the. automatic. stopvalve, and.

a connection. to that portion of the controlline leading .from said.control valve. a pair 05, valve. devices. in said. body, and. fluid.pressureoperated means in the body. for effecting. operation of. said.valve devices,. said valves fluid. operated. means serving to admit airfrom. the main.r.eser-- voir supp y to that. portion of. the control.line. leading. from the stop valve at the end of. the forestalling.cycle: and until: the. pneumatic pressure. in that portion of. the.control line leading. from. the. control. valve has been. built up tosub.- stantially normal value...

7.. In. a line. charger, a body having a. passage. for oonnectionwith asource of. air under pressure, a. second. passage. having connectionwitha.

line: to. be. charged with. airand. a third. passage. for connection.with a. line. which. is. adapted. for communication.- withsaid first.named. line,.a pair. oi'valve meanswithin.saidhody,.each valve means:including avalve member. movablein opposite directions between openandclosed.positi0n,,a.stationary seatformed. withmthevalve bodyandhooperating withsaidl valve member, a valve. stem attachedtoeachvalvemember, and a. valve orifice formed in. one end or said stem,said valve body being provided withtwo spaces'on that side oi each. of.the, stationary valve seats whi'chthe' corresponding, valve memberengages. the first. space. being in communication. with. the first namedpassage,, the second space. being in communication with the third namedvpassage}. 2. vented space within the body in communication. with theendsofsaid valvestems and also in coma-- munication with the atmosphere,an intermediate space in the valve body located intermediate" the valve.seats. and saidlast. named vented space,.sald intermediate. spaceserving to interconnect both. the. first andsecond spaces, whensaidlvalve mem;-- bers are. in open -position,.aligned cylinders formed;in the; valve.- bod'v,. a pair. of. aligned. pistons di'sposed withinsaid cylinders, a. yoke bar interposed. between. said pistons. andhaving, seating, surfaces. formed. on their. end portionsadapted. toengage theadiiacent ends of; the=valvestems,,meansform-- ing. a.pneumatic. connection. between the. space on one. side of. one ofithepistons .andsaid third. line,! aflow restricting. orificeinterconnectingthaspace on one sideot. the other onemf. saidlpistons.with said second line, and. a cavity or chamber likewiseincommunication. with said. last: named. space,- said pistons functioning,in response to. pneumatic. pressure applied to the. same to move.saidyoke. bar in. opposite directions between limiting. posl-- tions,the. valve members. in one. limiting. position. being, both. open andhaving the. orifices. in.

- 13 their stems closed, and in the other limiting positions the valvemembers being both closed and said yoke bar being free with respect tothe ends of the stems whereby said intermediate space is vented to theatmosphere through said stem orifices.

8. In a line charger, a body having a passage for connection with asource of air under pressure, a second passage having connection with aline to be charged with air, and a third passage for connection with aline which is adapted for communication with said first named line, apair of valve means within said body, each valve means including a,valve member movable in opposite directions between open and closedposition, a stationary seat formed within the valve body and cooperatingwith said valve member, a I

valve stem attached to each valve member, and a valve orifice formed inone end of said stem, said valve body being provided with two spaces onthat side of each .of the stationary valve seats which the correspondingvalve member engages, the first space being in communication with thefirst named passage, the second space being in communication with thethird named passage, :a vented space within the body in communicationwith the ends of said valve stems and also in communication with theatmosphere, an intermediate space in the valve body located intermediatethe valve seats and said last named vented space, said intermediatespace serving to interconnect both the first and second spaces when saidvalve members are in open position, aligned cylinders formed in thevalve body, a pair of aligned pistons disposed within said cylinders, ayoke bar interposed between said pistons and having seating surfacesformed on their end portions adapted to engage the adjacent ends of thevalve stems, means forming a pneumatic connection between the space onone side of one of the pistons and said third line, a flow restrictingorifice interconnecting the space on one side of the other one of saidpistons with said second line, and a cavity or chamber likewise incommunication with said last named space, said pistons functioning inresponse to pneumatic pressure applied to the same to move said yoke barin opposite directions between limiting positions, the valve members inone limiting position being both open and having the orfic'es in theirstems closed, and in the other lim-- iting positions the valve membersbeing both closed and said yoke bar being free with respect to the endsof the stems whereby said intermediate space is vented to the atmospherethrough said stem orifices. I

9. In a pneumatic train braking system as in claim 4 in which said linecharging means incorporates means serving to automatically interruptsupply of supplemental charging air to the control line .at the end of ashort charging period irrespective :of operation of the control valveduring such interval.

10. In a pneumatic train braking system including a control valveadapted to be opened in response to a track impulse to vent a controlline and an automatic stop valve connected to the control line wherebywhen the control line is vented said automatic stop valve vents the mainbrake pipe of the train braking system, a shut-off valve in the controlline and adapted in one position of the same to close that portion ofthe control line leading to the automatic stop valve and to Vent thatportion of the control line leading to said control valve, said shut-offvalve in the other position of the same serving to re-establishcommunication between both portions of the control line, and linecharging meansconnected to that portion of the control line leading fromthe automatic stop valve and serving for a short charging interval toautomatically supply said portion :of the control line with supplementalair under pressure to recharge the entire contro1 line when saidshut-ofi valve is moved to said other position to re-establishcommunication between both portions of the control line, said linecharging means also serving to automatically interrupt such supply ofsupplemental air at the end of said charging interval.

HERBERT P. FOLKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Farmer Oct. 2, 1928

